REGULATION OF IGG PRODUCTION BY SUPPRESSOR FC-GAMMA-RII+ T-HYBRIDOMAS

In this work, we analyzed the immunoglobulin heavy (H) and light (L) chain production by two variant B hybridomas, UN2.C3 and UN2.C17.K1 co‐cultured with cells from a FcγRII, IgG‐binding factor (IgG‐BF)‐producer T hybridoma (T2D4.C1) or with cells of a FcγRII−, IgG‐BF‐nonproducer variant (D10C5). We showed that only the FcγRII hybridoma directly inhibits the IgG secretion by UN2.C3 through a soluble mediator. This inhibition affects the H and L chain synthesis as well as the H and L chain‐encoding mRNA steady state. No apparent cytotoxic effect could be detected. In contrast, the production of ϰ chain by an H chain‐negative variant (UN2.C17.K1) was unaffected. This indicates that a complete IgG molecule is required to observe the inhibitory effect induced by T2D4.C1. The pattern of effector/target cell interactions observed in our work suggests that the soluble factor involved in the suppression of IgG production is IgG‐BF, able to transiently modify the IgG gene expression in target cells. Copyright © 1990 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim